WTF.
...engine was running fine, and nothing was out of the ordinary, so I pulled into a parking spot and shut the engine off. Waited a few seconds and restarted it, and the gauges came back and worked perfectly fine all the way home.
And of course it has to happen a week before I have to start commuting. Perfect.
Plus side, the engine ran fine; what I'm seeing on-line says that the two most common failure modes are one where the engine runs--in which case it's just a bad connection at the instrument cluster--or the engine does not run, which indicates that the crankshaft position sensor has failed.
So tomorrow I get to take 'er to a parts store and have the codes read, just to make sure; after which I'm going to pull the instrument cluster and clean all the connectors. And pray to God that this doesn't turn into the non-running variety of failure.
*sigh*
There are a few quirks that the Jeep has displayed over the past eight years, electrical in nature. For example, sometimes when I signal a left turn, the relay rattles and the light doesn't come on or start blinking. If I shut off the indicator and turn it back on, it works normally.
There was all kind of animal hair in the nooks and crannies, like under the front seats--straight hair--and the damage that the thing's had since before I bought it suggested to me that it had hit a deer that ended up in the passenger compartment--which is why the front edges of the fenders are wrinkled and there's that crease in the A-pillar on the passenger side, and also why the paint on the nose piece doesn't quite match the rest of the truck. The wrinkles are why I got a $8,000 truck for $5,000, and the cosmetics have not really bothered me all that much. The owner's manual looks like it was left to moulder in a swamp for a few months, which suggested to me that the interior had been open to the elements for a while.
All these are things that I discovered/figured out after buying the truck, but everything worked fine and it didn't smell bad or anything. And it's been a jim dandy vehicle.
Hopefully this is just another minor thing for me to attend to, and it won't turn into a gigantic clusterfuck. But if it does, well, I'll just have to figure out how to manage, is all.